Safety-bolster

ABSTRACT

An over-load control for a bolster plate to be positioned on the ram portion of a press, wherein, the device includes a cavity pressureized by a controlled fluid pressure for supporting the bolster plate with means to relieve the pressure upon over-load, said pressurized system being self contained in the bolster plate.

United States Patent 1191 Zupan, Jr. et a1;

[5 1 SAFETY-BOLSTER [76] Inventors: Benjamin J. Zupan, Jr.; Leonard S.Zipp, Jr., both of 1 1090 Abbey Rd,

both of North Royalton, Ohio 44133 [22] Filed: Apr. 7, 1971 211 Appl.No.: 131,982

[52] US. Cl 72/432, 72/441, 100/53 [51] Int. Cl. 321d 55/00 [58] FieldOf Search 72/432, 453, 441; 100/53; 192/150 [56] References Cited UNITEDSTATES PATENTS 1,773,439 8/1930 Rode 72/432 2,890,669 6/1959 Williamson72/432 2,936,055 5/1960 Kassnel 72/432 [4 June 18, 1974 2,998,238 8/1961Kenline 72/432 3,481,171 12/1969 Alexander 72/432 3,487,772 1/1970 Kraft1 1 100/53 3,583,201 6/1971 Topaz 72/432 FOREIGN PATENTS OR APPLICATIONS1,177,006 8/1964 Germany 100/53 Primary E.vaminerCharles W. LanhamAssistant Examiner-Gene P. Crosby 5 7] ABSTRACT An over-load control fora bolster plate to be positioned on the ram portion of a press, wherein,the device includes a cavity pressureized by a controlled fluid pressurefor supporting the bolster plate with means to relieve the pressure uponover-load, said pressurized system being self contained in the bolsterplate.

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ATTOENEV SAFETY-BOLSTER This invention relates to safety apparatus forpreventing damageto a punching or cutting machine by overloading theframe and shafts as a result of faulty transfer ofmaterial through thedies, misalignment, or other accidents and more particularly to a safetybolster plate, wherein the supportingmedium is a hydraulic fluidarranged with controls for providing a movement of the plate whencertain predetermined overload conditions are encountered.

An important object of this invention is to provide a tool supportcapable of shifting and relieving an excessive load on the machine framesaid support having apparatus therein which measures the force thereonand operates at a predetermined loading.

Spring trip devices are known in the art for releasing tolling or movingparts of a machine as a means of pre venting damage to the machineryframe and mechanical parts. The apparatus which forms the preferredembodiment of our invention utilizes hydraulic principals and becomespart of the machine itself thus making it operable at all timesirrespective of the tooling on the equipment. Further the system doesnot rely on springs pressure sufficient to hold the same against normalmachine loadings. When a fault occurs and the machine loading exceeds anormal limit the pressure in the bolster plate rises and isautomatically relieved which allows the plate to shift thus reducing theload on the machinery frame. The control apparatus for the hydrauliccircuit includes a shut-off for the machinery.

Accordingly, it is an important object of this invention to provide abolster plate for a punch or shear machine wherein the working surfaceis maintained in operative position by the action of hydraulic pressurerelievable upon a predetermined excessive stress of the plate.

Another importantobject of this invention is to provide a bolster platefor a press-type machine wherein the working surface of the bolsterplate is carried by a hydraulic fluid said bolster plate including anoil pump and pressure regulating apparatus for maintaining a constantand predetermined support pressure for the bolster plate.

An important object of this invention is to provide a tool supportcapable of shifting and relieving an excessive load on the machine framesaid support including apparatus which measure the force thereon andoperates at a predetermined loading.

Other objects and advantages more or less ancillary to the foregoing,and the manner in which all the various objects are realized, willappear in the following description, which considered in connection withthe accompanying drawings, set forth in the preferred embodiment of theinvention. In the drawings:

FIG. 1 is a top plan view with parts cut away for purposes of clarity;

FIG. 2 is a sectional view taken along line 2-2 in FIG. 1;

FIG. 3 is a side view with cut-away portion showing an alternate bolsterplate in section;

FIG. 4 is a sectional view taken along line 4--4 of FIG. 1; and

FIG. 5 is a front view.

Referring first to FIG. 1, the safety bolster device is shown thereinhaving an upper plate 10 substantially rectangular in shape'and having acentral opening .12 formed therein. The opening 12 threadably receives asleeve 14 extending downwardly from the upper plate 10. Thesleeve 14 isprovided with a cylindrical opening 16 formed there through.

The sleeve 14 is threadably mounted in plate 10 as at 18. The upperplate 10 provides a surface on which the tooling is carried by the punchpress (not shown) for operation with the press ram there above.

The safety bolster assembly includes a lowerplate. 20 on which the upperplate 10 is slidably mounted said upper plate 10 being verticallyreciprocable in'respect to the lower plate 20. Upper plate 10 has adepending rim 22 which is slidably on a wall 24 formed on the bottomplate 20. O-ring seals are provided around the periphery of the innerwall of the rim 22 and the wall 24 of the lower plate 20 and provide afluid-tight seal there between. The lower plate 20 is provided with acylindrical opening 28 for slidably receiving sleeve 14. O-ring seals 30in the lower plate 20 engage the outer surface of the sleeve 14 andprovide a fluid-tight seal between the sleeve 14 and the lower plate 20.

The lower plate 20 has a circular shoulder 32 confronting a circularshoulder 34 formed on the sleeve 14, said shoulders providing a stopwhich limits the vertical movement of the plate 10 in respect to plate20 and in respect to the machine. When the shoulder 32 and 34 are incontact, a cavity 36 results between the upper plate 10 and the lowerplate 20 said cavity 36 being filled with hydraulic oil contained!therein by the seals 26 and 30. When the hydraulic fluid is applied tocavity 36 under pressure the upper plate is moved to its operationalposition wherein the soulder 32 and 34 are in full contact.

A chamber 38 is formed in the lower plate 20 and is utilized as areservoir for containing hydraulic'fluid said chamber 38 providing asump for receiving oil from the cavity 36 and supplying oil as requiredfor introduction into the cavity 36 during the operation of the bolsterplate.

. A fluid passage 40 as shown in FIG. 2 opens to the cavity 36 beneaththe top plate 10 and above the lower toward the seat 44. Aplug 52threadably mounted in the lower plate 20 provides for adjusting the biason said spring and thereby achieve an adjustment of the pressure of thefluid in the cavity 36 which will urge the ball 46 off the seat 44 andallow the passage of hydraulic fluid from the cavity 36 to the bore 54which carries the spring 50 and the ball 46. The bore 54 opens through aport 56 to the reservoir 38 thus providing a fluid circuit from thecavity 36 to the reservoir 38. Plug 52 has an O-ring seal 58 at theforward end thereof which engages the bore 54 and prevents the passageof fluid through the threaded section of the bore 54.

An electrical conductor 60 is connected to seat 44 at one end and at theother endis joined to one pin 62 of electrical connector 64. Pin 66 ofsaid connector 64 is grounded tolower plate 20. The ball 46 acts as anormally closed switch when it is in the seated position. Upon actuationthereof and being lifted off the seat 44 by pressure in the cavity 36,the circuit is opened and a connection from the conductor 64 may be madeto the machine controls for stopping the machine upon actuation of theball 46 off the seat 44.

The piston 68 is slidably in a cylinder sleeve 70 and carries a pair ofO-rings seals 72. Actuation of said piston 68 in one direction increasesthe fluid pressure in the cylinder bore 74. An inlet check valve 76carries a ball 78 biased against a seating a spring 80, said check valve76 being in a passage 82 which provides a conduit for the hydraulicfluid to the pump 74 from the valve bore 54 and the reservoir 38.Acutuation of the piston 68 away from the check valve 76 results inhydraulic fluid flowing into the pump cylinder and being ejected throughpassage 84 upon a return stroke of said piston 68 in the oppositedirection, said fluid being ejected through the passage 84 to the cavity36 by way of passage 40 between the upper plate and the lower plate 20.A ball check valve 86 in the passage 84 obstructs the flow of the fluidfrom the cavity 36 to the pump 74, a ball 88 being biased against a seatby a compression spring 90. Reciprocal movement of the piston 68alternately takes hydraulic fluid from the reservoir 38 and ejects itinto the cavity 36.

Piston 68 is connect through a link 92 to handle 94 which is pivotallymounted on the lower plate by a pin 96. Angular displacement of thehandle 94 results in reciprocal movement of the piston 68 thus allowingthe operator to pump up the pressure in the cavity 36 by actuation ofhandle 94.

A pressure gage 98 is hydraulically connected to the cavity 36 andprovides the operator with an indication of the pressure therein and theavailable force on the plate to hold the same in position against theforce of the ram or other normal machine stresses. I

Having thus described this invention in such full, clear, concise, andexact terms as to enable any person skilled in the art to which itpertains to make and use the same, and having set forth the best modecontemplated of carrying out this invention, we state that the subjectwhich we regard as being our invention is par ticularly pointed out anddistinctly claimed in what is claimed, it being understood thatequivalents or modifications of, or substitutions for, parts of theabove speciflcally described embodiments of the invention may be madewithout departing from the scope of the invention as set forth in whatis claimed.

What is claimed is:

l. A safety bolster plate comprising an upper plate verticallyreciprocable on a lower plate, fluid seal means between said platesoperable with said upper and lower plates to form a fluid-tight cavity,fluid reservoir means, pump means connected to said fluid reservoir andsaid cavity for pressurizing the fluid in said cavity, stop means onsaid upper and lower plates for limiting relative movement therebetweenin one direction, the pressurized fluid urging said plates against saidstop means, and pressure-controlled valve means for limiting thevfluidpressure in said cavity, said fluid being vented to said reservoir whenthe pressure in said cavity is raised to a predetermined point by a loadon said upper plate.

2. The apparatus of claim 1 wherein said pressure controlled valve meanscomprises a spring loaded ball valve having a manual means forpre-adjusting the loading on the spring.

3. The apparatus of claim 2 wherein an electrical circuit is opened bythe actuation of said ball valve, said circuit controlling the operationof the machine and stopping same upon actuation of the safety bolsterplate.

4. The apparatus of claim 3 wherein gage means is carried by said lowerplate and indicates the pressure of fluid in the cavity between theplates.

5. The apparatus of claim 1 wherein electrical circuit means is openedby the actuation of the pressure controlled valve means.

6. The apparatus of claim 1 wherein said stop means comprises a shoulderon said sleeve opposite to the upper plate, said lower plate having ashoulder confronting said sleeve shoulder, said shoulders contacting toprovide a positive stop limiting the travel of said plates as pressureis applied to the fluid in the cavity.

1. A safety bolster plate comprising an upper plate verticallyreciprocable on a lower plate, fluid seal means between said platesoperable with said upper and lower plates to form a fluidtight cavity,fluid reservoir means, pump means connected to said fluid reservoir andsaid cavity for pressurizing the fluid in said cavity, stop means onsaid upper and lower plates for limiting relative movement therebetweenin one direction, the pressurized fluid urging said plates against saidstop means, and pressure-controlled valve means for limiting the fluidpressure in said cavity, said fluid being vented to said reservoir whenthe pressure in said cavity is raised to a predetermined point by a loadon said upper plate.
 2. The apparatus of claim 1 wherein said pressurecontrolled valve means comprises a spring loaded ball valve having amanual means for pre-adjusting the loading on the spring.
 3. Theapparatus of claim 2 wherein an electrical circuit is opened by theactuation of said ball valve, said circuit controlling the operation ofthe machine and stopping same upon actuation of the safety bolsterplate.
 4. The apparatus of claim 3 wherein gage means is carried by saidlower plate and indicates the pressure of fluid in the cavity betweenthe plates.
 5. The apparatus of claim 1 wherein electrical circuit meansis opened by the actuation of the pressure controlled valve means. 6.The apparatus of claim 1 wherein said stop means comprises a shoulder onsaid sleeve opposite to the upper plate, said lower plate having ashoulder confronting said sleeve shoulder, said shoulders contacting toprovide a positive stop limiting the travel of said plates as pressureis applied to the fluid in the cavity.